Apparatuses for adjusting electrode gap in capacitively-coupled rf plasma reactor

ABSTRACT

A plasma processing chamber includes a cantilever assembly configured to neutralize atmospheric load. The chamber includes a wall surrounding an interior region and having an opening formed therein. A cantilever assembly includes a substrate support for supporting a substrate within the chamber. The cantilever assembly extends through the opening such that a portion is located outside the chamber. The chamber includes an actuation mechanism operative to move the cantilever assembly relative to the wall.

BACKGROUND

Integrated circuits are typically formed from a wafer over which areformed patterned microelectronics layers. In the processing of thesubstrate, plasma is often employed to deposit films on the substrate orto etch intended portions of the films. Shrinking feature sizes andimplementation of new materials in next generation microelectronicslayers have put new demands on plasma processing equipment. The smallerfeatures, larger substrate size and new processing techniques createadditional demands on control of the plasma parameters, such as plasmadensity and uniformity across the substrate, to achieve desired yields.

SUMMARY

An exemplary embodiment of a plasma processing apparatus comprises achamber comprising a wall surrounding an interior region and having anopening; a cantilever assembly comprising: an arm unit extending throughthe opening of the wall and having an outer portion located outside theinterior region; and a substrate support on the arm unit and disposedwithin the interior region; an actuation mechanism coupled to the outerportion of the arm unit and operative to move the cantilever assemblyrelative to the wall; and at least one vacuum isolation member enclosinga space partially surrounded by the outer portion of the arm unit andthe wall and being in fluid communication with the interior region, thevacuum isolation member providing vacuum isolation for the space suchthat an atmospheric load on the cantilever assembly is neutralized.

An exemplary embodiment of a plasma processing chamber for processing asubstrate comprises a wall surrounding an interior region and having anopening; a cantilever assembly extending through the opening, thecantilever assembly including a substrate support surface at a first endinside the interior region and a second end outside the interior region;and an actuation mechanism coupled to the second end and operative tomove the cantilever assembly in reverse directions perpendicular to thesubstrate support surface.

An apparatus for adjusting an inter-electrode gap in acapacitively-coupled plasma processing chamber comprising an upperelectrode assembly and a wall surrounding an interior region and havingan opening, the apparatus comprising a cantilever assembly including alower electrode, a substrate support surface at a first end and a secondend, the cantilever assembly being adapted to extend through the openingsuch that the first end is inside the interior region and the second endis outside the interior region; and an actuation mechanism coupled tothe second end and operative to move the cantilever assemblyperpendicular to the substrate support surface.

DRAWINGS

FIG. 1 shows a schematic diagram of a capacitively-coupled plasmaprocessing chamber.

FIG. 2 is a schematic cross-sectional diagram of an embodiment of acapacitively-coupled plasma processing chamber including a cantileverassembly.

FIG. 3 shows an enlarged view of region A shown in FIG. 2.

FIG. 4 shows a schematic top view of the CAM ring and motor shown inFIG. 2.

FIG. 5 shows an enlarged schematic view of region B shown in FIG. 2.

DETAILED DESCRIPTION

FIG. 1 illustrates a capacitively-coupled plasma processing chamber 100of a plasma processing apparatus. As depicted, a lower electrodeassembly includes a focus ring 108; and a chuck 104 for holding asubstrate 106 in place during operation of the chamber. The chuck 104 issupplied radio frequency (RF) power by an RF power supply 110. In theillustrated chamber 100, the lower electrode assembly is fixed to thechamber wall 118. An upper electrode assembly includes an upperelectrode 114; a baffle 116; and a cylindrical body 123 from which theupper electrode and baffle suspend. The upper electrode 114 can begrounded or powered by another RF power supply 120 during operation. Gassupplied through the baffle 116 and upper electrode 114 is electricallyexcited to produce plasma in the gap 125. Plasma in the gap 125 isconfined by confinement rings 102. Some of the gas in the plasma passesthrough spacing/gaps between the confinement rings 102 and is exhaustedfrom the chamber.

In the illustrated chamber 100, to adjust the gap 125 between the lowerand upper electrode assemblies, the entire upper electrode assembly israised or lowered by an actuator mechanism 124. A sealing arrangement126 may be used to provide a vacuum seal between the cylindrical body122 and the reactor top 112 while allowing the upper electrode assemblyto move relative to the lower electrode assembly. A portion 123 of thecylindrical body 122 is subject to atmospheric pressure, while theremainder of the upper electrode assembly is subject to low pressures.As the upper electrode assembly moves as one integral body, thesummation of pressure on the surface of the upper electrode assemblyyields a downward force, referred to as atmospheric load. In other typesof chambers, the lower electrode assembly may be moved up and down toadjust the gap, while the upper electrode may be stationary. In suchchambers, because the top and bottom sides of the lower electrodeassembly are respectively subject to a low pressure and atmosphericpressure, the lower electrode assembly is subject to an atmospheric loaddirected upwardly.

In the embodiment, the atmospheric load depends on parameters includingthe diameter of the upper electrode 114, the cross-sectional dimensionof the cylindrical body 122, the pressure of the plasma in the gap 125,and the chamber pressure within the top 112. Because the atmosphericload is present while moving the upper (or lower) electrode assembly,and the atmospheric load can vary, it is desirable to have acapacitively-coupled chamber that can neutralize the atmospheric load,to thereby allow the gap to be controlled more accurately.

FIG. 2 shows an exemplary embodiment of a capacitively-coupled plasma(CCP) processing chamber 200 of a plasma processing apparatus. Thechamber 200 can neutralize the atmospheric load to allow accuratecontrol of the electrode gap. The chamber 200 comprises a wall 204; anupper electrode assembly 202 mounted to the wall; and a chamber top 206enclosing the top portion of the upper electrode assembly 202. The upperelectrode assembly 202 comprises an upper electrode 203; and one or morebaffles 205 including gas passages for distributing process gas into agap 207 defined between the upper electrode 203 and the lower electrodeassembly 212. For brevity, the upper electrode assembly 202 is shown tohave three components. However, the upper electrode assembly can includeadditional components. The wall 204 has a gate 208 through whichsubstrates are unloaded/loaded into the chamber 200.

For brevity, only one gas line is shown in FIG. 2. Additional gas linescan be coupled to the upper electrode assembly 202, and the gas can besupplied through other portions of the chamber wall 204 and/or thechamber top 206.

The chamber 200 comprises a cantilever assembly 210 that is raised orlowered by an actuation mechanism 228. The cantilever assembly 210includes a cantilever arm 214, outer conducting ring 241, the lowerelectrode assembly 212, and an insulator 238 for electrically insulatingthe outer conducting ring 241 from the lower electrode assembly 212. Thelower electrode assembly 212 is shown to have one component. However,the lower electrode assembly 212 can include additional components, suchas a lower electrode and chuck for holding a substrate in place on thetop surface of the lower electrode assembly 212 during operation. Thechuck can be an electrostatic, vacuum, or mechanical chuck. The lowerelectrode is typically supplied with RF power from one or more RF powdersupplies 216. The RF power can have a frequency of, for example, 2 MHzto about 27 MHz. The RF power excites the process gas to produce plasmain the gap 207. Other suitable mechanisms, such as a lift pin mechanismfor lifting the substrate, optical sensors, and a cooling mechanism forcooling the lower electrode assembly 212, are attached to or formportions of the lower electrode assembly 212. The facility components224 collectively represent these other types of mechanisms.

The arm 214 can have a generally cylindrical tube shape. The arm 214 ispreferably formed of a conducting material. As the outer surface of thearm 214 is exposed to reactive process gases, the arm 214 can have anouter protective coating, or can be formed of a material, such asstainless steel, that can withstand process gas. The cantilever assembly210 also includes an upper arm support 226 and a lower arm support 220secured to the arm 214. Hereinafter, the arm 214, upper arm support 226,and lower arm support 220, are also collectively referred to as an armunit. As the upper arm support 226 and lower arm support 220 are locatedoutside the side wall 204, these components are also referred to hereinas an outer portion of the arm unit. The lower arm support 220 includesa cylindrical tube portion 221 that forms a supply line path 222.Facility supply lines, such as coolant pipes, pneumatic lines, sensorinput/output lines, for the facility components 224 pass through thesupply line path 222 extending from the inner space of the cylindricaltube portion 221 of the lower arm support 220 to the bottom surface ofthe lower electrode assembly 212. The supply line path 222 forms acavity inside the cantilever assembly 210 and is open to the atmosphere.The lower arm support 220 can be formed of conducting material.

The upper arm support 226 includes a generally cylindrical tube portion227 and a top plate 229. One end of the top plate 229 is secured to theactuation mechanism 228. The top plate 229 also supports the RF supplyor match 216. The cylindrical tube portion 227 of the upper arm support226 and the arm 214 provide a space for accommodating an L-shaped RFtube assembly 218. The components of the cantilever assembly 210, i.e.,the lower electrode assembly 212; arm 214; RF tube assembly 218; lowerand upper arm supports 220, 226; outer conductor ring 241; and insulator238 are moved up and down as one integral body by the actuationmechanism 228 so that the gap 207 is adjusted. Further details of theactuation mechanism 228 are described below in conjunction with FIG. 3.

The bottom of the wall 204 is coupled to a vacuum pump unit 239 forexhausting gas from the chamber. The chamber 200 includes at least onevacuum isolation member to provide vacuum isolation for the cantileverassembly 210. In the illustrated embodiment, the vacuum isolation membercomprises two bellows 230 a, 230 b. The outer surfaces of the lower andupper arm supports 220, 226, and the outer surface of the arm 214 aresubject to lower pressures generated by the vacuum pump unit 239.Considering a substrate as a part of the cantilever assembly 210, it canbe realized that most of the outer surface of the cantilever assembly210 is located within low pressure regions during operation. As such,the atmospheric load on the cantilever assembly 210, i.e., the total gaspressure around the outer surface of the cantilever assembly 210, isinsignificant, i.e., the atmospheric load is neutralized. As theatmospheric load is neutralized in the embodiment, the cantileverassembly 210 delivers a reduced load to the actuation mechanism 228.

Process gas injected into the gap 207 is energized to produce plasma toprocess the substrate, passes through the confinement ring assembly 246,and stays in the space surrounding the outer surfaces of the lower armsupport 220, upper arm support 226, and arm 214 until exhausted by thevacuum pump unit 239. As the upper and lower arm supports 220, 226 areexposed to reactive process gas during operation, they are formed ofmaterial, such as stainless steel, that can withstand the process gas orhave protective coatings. Likewise, the bellows 230 a, 230 b are formedof a material that can withstand the chemistry, such as stainless steel.The diameter of the bellows 230 a, 230 b may vary depending on thedesign requirements and can be about 1.6 cm to about 3.6 cm, forinstance.

The cantilever assembly 210 is raised or lowered to adjust the gap 207between the upper electrode assembly 202 and a substrate mounted on thelower electrode assembly 212. To decrease the gap 207, the cantileverassembly 210 is raised to compress the upper bellows 230 a and tostretch the lower bellows 230 b. Likewise, to increase the gap 207, thecantilever assembly 210 is lowered to stretch the upper bellows 230 aand to compress the lower bellows 230 b.

In the embodiment, the volume of the region of the chamber 200 at vacuumpressure substantially does not change during vertical movement of thecantilever assembly 210, which is entirely within the volume defined bythe inner surface of the wall 204, the outer surface of the cantileverassembly 210, and bellows 230 a, 230 b. The volume can be maintainedsubstantially constant because when the cantilevered assembly 210 ismoved upwardly, bellows 230 a expands and bellows 230 b contracts,thereby maintaining substantially the same volume within the vacuumregion. As shown in FIG. 2, although the bellows 230 a, 230 b areslightly off center with respect to their vertical axes, the dualbellows balance the atmospheric load by maintaining the internal volumeof the chamber 200 substantially constant at various vertical positionsof the cantilevered assembly 210. In this way, atmospheric pressure onthe top of the cantilevered assembly above the chamber 200 counteractsthe atmospheric pressure acting on the interior of supply line path 222.Because the volume change is insignificant during the gap adjustment andthe atmospheric load is balanced, there is reduced fluctuation of thechamber pressure and plasma pressure. Thus, the atmospheric load hasminimal influence on process conditions within the chamber 200.

As described above, the facility supply lines pass through the supplyline path 222. The supply line path 222 extends from the cylindricaltube portion 221 of the lower arm support 220 through the arm 214 to thefacility components 224 located under the lower electrode assembly 212.The support line path 222 is open to the atmosphere. However, as thepath 222 forms a cavity in the cantilever assembly 210, the summation ofthe atmospheric pressure on the cavity surface does not yield anyatmospheric load.

The RF supply 216 supplies RF power to the lower electrode assembly 212during operation. The RF supply 216 sends RF energy through the L-shapedRF tube assembly 218. The upper section 218 a of the RF tube assembly218 is located inside the cylindrical portion 227 of the upper armsupport 226, while the lower section 218 b is located inside the arm214. The bottom portion of the upper section 218 a is coupled to an openend of the lower section 218 b to form a cavity for RF transmission. TheRF tube assembly 218 is formed of a suitable conducting material. An RFconductor 240 located near the closed end of the lower section 218 bcollects the RF energy transmitted through the RF tube assembly 218 andsends the collected energy to the lower electrode assembly 212.

The level of RF matching between the RF supply 216 and RF conductor 240depends on the dimension of the RF tube assembly 218. The lengths anddiameters of the upper and lower sections 218 a, 218 b of the RF tubeassembly 218 preferably have optimum values so that the RF powerdelivered through the tube assembly 218 is optimized in a wide RFfrequency range. In the illustrated embodiment, both the upper section218 a and the lower section 218 b of the RF tube assembly 218 are movedwith the RF supply 216 during the gap adjustment. Thus, once the RF tubeassembly 218 is set to its optimum configuration, the configuration canbe maintained without further adjustment, resulting in enhancedperformance of the chamber 200 over a wide range of RF frequency.

In the embodiment, vertical movement of the cantilevered assembly 210(i.e., vertical to the substrate support surface provided on the arm214) can be effected without sliding parts inside the chamber 200.Consequently, the cantilevered assembly 210 reduces potential forparticle generation during gap adjustment. For instance, because theupper end of one end of the horizontal arm 214 is located outside thechamber, the horizontal arm 214 and substrate support can be raised andlowered as a unit without use of a vertical drive mechanism inside thechamber, or sliding parts to accommodate expansion of a bottom electrodeassembly. Likewise, because software used to control supply of RF powerto the lower electrode moves as a unit with the horizontal arm andsubstrate support, the RF supply line can be made from rigid conductingmaterials at a preset length as there is no need to accommodate movementbetween the lower electrode and the RF supply, which otherwise occurswhen the software is located on a fixed surface outside a plasmachamber.

The gas in the gap 207 is electrically excited to produce plasma by theRF power delivered to the lower electrode assembly 212. The returncurrent, which is the current flowing from the lower electrode assembly212 through the plasma to the upper electrode assembly 202, needs toreturn back to the RF supply 216 to complete a current loop. In thechamber 200, several flexible contacts or strips 234 are used to makesecure electrical connection between the wall 204 and the outerconductor ring 241 that is electrically coupled to the arm 214. Theouter conductor ring 241 is formed of conducting material andelectrically separated from the lower electrode assembly 212 by theinsulator 238. The return current completes the loop by flowing from theupper electrode assembly 202 through the wall 204, flexible contacts234, outer conductor ring 241, arm 214, wall or shield of the RF tubeassembly 218, to the RF supply 216. The bellows 230 a, 230 b do not forma part of the circuit for the return current. A conductor component 236is used to electrically connect the arm 214 to the wall of RF tubeassembly 218, providing an additional path for the return current.

As the outer conductor ring 241 moves relative to the wall 204 duringgap control or substrate loading/unloading, the contacts 234 aresufficiently flexible to accommodate the relative motion. The flexiblecontacts 234 are preferably formed from a metal alloy, such as berylliumcopper (BeCu). Optionally, the contacts 234 can have a plasma resistantcoating to protect them from reactive process gases. The flexiblecontacts 234 are stretched or compressed due to the relative motionbetween the wall 204 and conductor ring 241. The contacts 234 may have acurved shape to provide stress relief.

As described above, process gas is excited to produce plasma in the gap207. Once plasma is generated in the gap 207, the confinement ringassembly 246 is operable to confine the plasma at different pressuresand gas flow conditions. In the embodiment, the confinement ringassembly 246 is actuated by a CAM ring/plunger assembly 250. The CAMring/plunger assembly 250 includes a CAM ring 242; a motor 244 forrotating the CAM ring 242; and plunger assemblies coupled to the CAMring 242 and confinement ring assembly 246. Further details of theconfinement ring assembly 246 and CAM ring/plunger assembly 250 aredescribed below in conjunction with FIGS. 4 and 5.

In general, patterning microelectronic layers on substrates includesseveral etching/deposition steps. During the several steps, successivebyproduct layers are deposited on the surfaces of the upper and lowerelectrode assemblies. As the bonds between the byproduct layers and theassembly surfaces eventually weaken, the byproduct layers may peel orflake off from the surfaces to contaminate the substrate. In the chamber200, the upper electrode assembly 202 remains fixed while the cantileverassembly 210 is moved in the vertical direction to adjust the gap 207between the lower and upper electrode assemblies 212, 202. As such, mostof the flakes may fall off from the cantilever assembly 210 duringtransition between the steps or loading/unloading of substrates. As thesubstrate is located on top of the cantilever assembly 210, i.e., thesubstrate is located above the contamination region, the byproductcontamination may be significantly reduced, enhancing the manufacturingyield.

FIG. 3 is an enlarged schematic view of region A shown in FIG. 2,illustrating the actuation mechanism 228 (FIG. 2) for moving thecantilever assembly 210. As depicted, an end portion of the upper armsupport 226 is rotatably secured to the tip of a lead screw or ballscrew 306. A motor 304 secured to a support bracket 302 actuates thelead screw 306 via a belt 308 or other suitable motion transmissionmechanism. The bottom of the screw 306 is rotatably secured to thebracket 302. Guide 310 has a female threaded hole which mates with thelead screw 306. Because the guide 310 is secured to a wall 300, arotational motion of the lead screw 306 generates a vertical motion ofthe upper arm support 226, support bracket 302, and motor 304. The typeof motor 304 and the pitch of the threads formed in the screw 306 affectthe degree of precision in adjusting the gap 207, preferably to fewtenths of microns. The motor 304 is controlled by a motor control system312. The motor control system 312 can be coupled to a sensor formeasuring the size of the gap 207 so that the gap control is performedin a feedback control mode. Various types of in-situ detectors, such aslaser, inductive, capacitive, acoustic, linear variable differentialtransformer (LDVT) sensors, can be used as a gap sensor and locatedeither inside or outside the wall 204, depending on the type of sensor.

FIG. 4 is a schematic top view of the CAM ring 242 and motor 244 shownin FIG. 2. As depicted, the motor 244 is coupled to the CAM ring 242 viaa belt 404. The belt 404 is attached to the CAM ring 242 at points 406and 408. In an alternative embodiment, the belt 404 can wrap around theCAM ring 242. A tensioning arrangement 410 takes up the slack in thebelt 404 and pulls the CAM ring 242 toward motor 244 to urge the innersurface of the CAM ring 242 to be in rolling contact with rollers 412and 414. Three plunger assemblies 250 are coupled to the CAM ring 242.The plunger assemblies 250 actuate the confinement ring assembly 246, asdescribed below in conjunction with FIG. 5. The motor 244 is controlledby a motor control unit 420.

The chamber 200 can include one or more pressure sensors for measuringthe pressure in the gap 207 as well as in the space 270 between thechamber wall 204 and the cantilever assembly 210. Signals from thesensor(s) are sent to the motor control unit 420. The motor control unit420 is coupled to the pressure sensors, such that signals from thesensor(s) are sent to the motor control unit 420. As the chamberpressure is partially controlled by the confinement ring assembly 246,the motor control unit 420 and pressure sensor can operate in a feedbackcontrol mode.

Additional rollers can be used to define the center of rotation of theCAM ring 242. Three plunger assemblies 250 are shown disposed about theCAM ring 242. However, other embodiments can include a different numberof plunger assemblies.

FIG. 5 is an enlarged schematic view of region B shown in FIG. 2. Asdepicted, the plunger assembly 250 includes a wheel 502, which is shownto be in rolling contact with the CAM ring 242; and a backing plate 506.The wheel 502 is adjustably mounted on the backing plate 506 via asuitable mechanism, such as bolt-and-slot arrangement. The backing plate506 is mounted on the chamber top 206 (FIG. 2) and is essentiallyimmobile with respect to the chamber top 206.

The assembly 250 also includes a plunger 504 and a CAM follower 508mounted on the plunger 504. The plunger 504 and CAM follower 508 areurged toward a lower surface 512 of the CAM ring 242 by a spring 510.The CAM follower 508 stays in contact with the lower surface 512 topermit the plunger 504 to rise or fall with the contours in the lowersurface 512. The plunger 504 moves up and down in a direction 540, whichis orthogonal to the plane defined by the WAP ring 532 and confinementrings 534.

A pair of seals 507 mounted in grooves formed in the upper electrodeassembly 202 permit the lower pressure within the chamber to bemaintained as plunger 504 moves up and down following the contour in thelower surface 512 of the CAM ring 242. Although two seals 507 are shown,other suitable number of seals can be employed as desired.

Vertical motion of the plunger 504 is controlled by the contour in thelower surface 512 of the CAM ring 242. As depicted in FIG. 5, the lowersurface 512 includes a CAM region 522. There is preferably one CAMregion for every plunger assembly 250. The CAM region 522 preferablyincludes an inclining surface 526, which causes the plunger 504 to bemoved downward as the CAM ring 242 rotates in the direction of arrow518. Alternatively, the declining surface 528 is not employed forcontrolling the plunger 504. Instead, the plunger 504 is moved upwardand downward by employing only the inclining surface 242 as the CAM ring504 is rotated back and forth and the CAM follower 508 follows thecontour of the inclining surface 526.

The inclining surface 526 can have two separate regions having twodifferent slopes. As shown, the first slope 530 is steeper than thesecond slope 524 to allow the plunger 504 to move upward and downward agreater distance per degree of rotation of the CAM ring 242. The slope530 may be used for coarse control while the slope 524 is used for finecontrol of the plunger 504. Alternatively, the inclining surface 526 mayhave one continuous slope.

The plunger 504 is coupled to the confinement ring assembly 246. Morespecifically, the bottom end of the each plunger 504 is coupled to theWAP ring 532 and a plurality of confinement rings 534 a, 534 b, 534 c(referred to herein collectively as confinement rings 534). The plungers504 move in the direction of arrow 540 to thereby control the locationof the rings 532, 534 and the gaps 536 a, 536 b, 536 c, 536 d(collectively referred to herein as gaps 536) between the rings 532,534. Process gas is introduced into the gap 207 through the upperelectrode assembly 202, which may include one or more baffles so thatthe process gas flows in the region 207 with a showerhead effect. In thegap 207, the process gas is excited to produce plasma to process asubstrate mounted on the top support surface of the lower electrodeassembly 212.

The gap 207, which is coaxial with the central axis of the substrate, isspaced from the wall 204 by virtue of the region including theconfinement ring assembly 246. The WAP ring 532 is coupled to the endsof plungers 250 and the rings 534 suspend from the WAP ring 532 via apost 538. The rings 532, 534 have a louver arrangement and the gaps 536between the rings are controlled to confine the plasma over a wide rangeof the gap 207. As the plungers 504 move upward, the rings 532, 534 getseparated from each other. As the plunger 504 moves downward or thecantilever assembly 210 moves upward, the bottom ring 534 a comes intocontact with the shoulder of the outer conductor ring 242. As thecantilever assembly 210 moves further upward, the gaps 536 b-536 dsequentially reduce to zero. Alternatively, a spacer may be inserted ineach of the gaps 536 to limit the minimum spacing between twoneighboring rings 534. Further details of the confinement ring assembly246 are found in commonly-owned U.S. Pat. No. 6,019,060, which is herebyincorporated by reference in its entirety. The rings 532, 534 arepreferably formed of a material having high electrical conductivity,such as silicon carbide having a high electrical conductivity of about2000 Ω-cm and able to withstand the harsh operational environment of theplasma in the gap 207. The rings 532, 534 may be formed of othersuitable conductive materials, such as aluminum or graphite. The post538 may be formed of metal.

The confinement ring assembly 246 assists in confining the plasma to thespace surrounded by the upper and lower electrode assemblies 202, 212and by the rings 532, 534, while allowing neutral gas constituents inthe gap 207 to pass through the gaps 536 in a generally horizontaldirection. Then, neutral gas constituents flow into the space 550surrounded by the inner surface of the wall 204, the outer surface ofthe cantilever assembly 210, and the bellows 230. The pressure in thespace 550 is controlled by the vacuum pump unit 239 attached to thebottom of the wall 204. As such, the confinement ring assembly 246separates the gap or plasma excitation region 207 from the space 550. Ingeneral, the volume of the gap region 207 is small compared to that ofthe space 550. Because the etch rate of the substrate is directlyaffected by the plasma in the gap 207, the assembly 246 enables a smallvolume pressure control and plasma confinement over the entire range ofthe gap 207 without major physical change to the chamber hardware. Also,as the volume of the gap 207 is small, the plasma conditions can becontrolled quickly and accurately.

Upon repeated use of the upper electrode assembly 202 and lowerelectrode assembly 212, the electrode surfaces facing the plasma aregradually eroded by the plasma. The gap 207 can be adjusted tocompensate for wear of the electrodes so that the process repeatabilityis maintained, and thereby the lifetime of the electrode is extended andcost of consumables is lowered.

While the invention has been described in detail with reference tospecific embodiments thereof, it will be apparent to those skilled inthe art that various changes and modifications can be made, andequivalents employed, without departing from the scope of the appendedclaims.

1-13. (canceled)
 14. A method of processing a semiconductor substrate,comprising: supporting a semiconductor substrate on the substratesupport in a plasma processing apparatus comprising: a chambercomprising a wall separating the interior of the chamber into first andsecond regions, the wall having an opening therein providing fluidcommunication between the first and second regions; a cantileverassembly comprising an arm unit extending horizontally through theopening such that a first end is in the first region and a second end isin the second region, a substrate support being located on an upperportion of the first end and a service conduit being located at thesecond end; an actuation mechanism coupled to an upper portion of theservice conduit and operative to move the cantilever assembly in avertical direction; wherein: the substrate support comprises a lowerelectrode assembly having a top surface adapted to support a substrate;the plasma processing chamber further comprises an upper electrodeassembly having a bottom surface facing and spaced from the top surfaceof the substrate support to form a gap therebetween; the lower electrodeassembly is coupled to a radio frequency (RF) power supply via an RFtransmission member located in the arm unit; and a dual bellowsarrangement providing a balanced atmospheric load on the interior of thechamber, the dual bellows including a first bellows providing a vacuumseal between an upper part of the chamber and the upper portion of theservice conduit and a second bellows providing a vacuum seal between alower part of the chamber and a lower portion of the service conduit;generating plasma in the space between the upper and lower electrodeassemblies; adjusting the gap by moving the cantilever assembly via theactuation mechanism, the atmospheric load on the cantilever assemblybeing neutralized during the adjusting; and processing the semiconductorsubstrate with the plasma.
 15. The method of claim 14, wherein theprocessing comprises plasma etching.
 16. A plasma processing chamber forprocessing a substrate wherein a wall separates the interior of thechamber into first and second regions in fluid communication via anopening in the wall, comprising: an actuation mechanism mounted on thechamber; an arm unit configured to extend horizontally through theopening such that a first end is in the first region and a second end isin the second region, a substrate support being located on an upperportion of the first end and a service conduit being located at thesecond end; an actuation member adapted to cooperate with the actuationmechanism, the actuation member being located at an upper portion of theservice conduit and operative to be driven such that the arm unit movesin a vertical direction.
 17. The plasma processing chamber of claim 16,wherein the service conduit extends in a vertical direction and includesvacuum seal locations at upper and lower portions thereof and a bellowsproviding vacuum seal between the chamber and the service conduit ateach of the vacuum seal locations.
 18. The plasma processing chamberclaim 16, wherein: (a) the substrate support includes an RF driven lowerelectrode and the service conduit includes a housing at the upperportion thereof, the housing containing circuitry providing an RF matchfor the electrode; (b) the service conduit includes at least one gasline operable to supply backside cooling to a substrate mounted on thesubstrate support: (c) at least one electrical connection operable totransmit signals from a sensor located in the substrate support: and/or(d) a fluid passage operable to circulate a heat transfer liquid in thesubstrate support.
 19. A capacitively-coupled plasma processing chambercomprising: an upper electrode assembly and a wall surrounding aninterior region in which a semiconductor substrate undergoes plasmaprocessing and a cantilever assembly including a lower electrode at afirst end, a substrate support surface at the first end and an actuatingmember at a second end, the cantilever assembly extending horizontallythrough an opening in the wall such that the first end is inside theinterior region and the second end is outside the interior region; andan actuation mechanism engaging the actuating member such that thecantilever assembly moves vertically to adjust an inter-electrode gapbetween the upper electrode assembly and the lower electrode.
 20. Theplasma processing chamber of claim 19, further comprising two bellowsconnected to an end of the cantilever assembly outside the interiorregion, the bellows providing vacuum isolation for the space inside theinterior region and outside the interior region such that an atmosphericload on the cantilever assembly is neutralized.
 21. The plasmaprocessing chamber of claim 19, wherein: the lower electrode is coupledto a radio frequency (RF) power supply via an RF transmission memberlocated in the cantilever assembly.
 22. The plasma processing chamber ofclaim 19, wherein the lower electrode comprises an electrostatic chuckoperable to clamp the substrate in place during plasma processing. 23.The plasma processing chamber of claim 19, wherein: the cantileverassembly comprises an internal cavity; and the plasma processing chamberfurther comprises: an RF tube located in the cavity and having one endcoupled to an RF power supply and being operative to transmit RF powerfrom the RF power supply therethrough; and an RF conductor coupled tothe other end of the RF tube and being operative to collect the RF powerand to send the RF power to the lower electrode.
 24. The plasmaprocessing chamber of claim 19, further comprising at least one flexibleconductor connected between the cantilever assembly and the wall. 25.The plasma processing chamber of claim 20, wherein: (a) the cantileverassembly includes a service unit which extends in a vertical directionand is open at the bottom thereof and/or (b) a first bellows isstretched while a second bellows is compressed when the cantileverassembly is moved upward by the actuation mechanism.
 26. The plasmaprocessing chamber of claim 19, wherein: the actuation mechanismcomprises: a ball screw rotatably secured to the cantilever assembly andoperative to move the cantilever assembly when rotated; and a motor forrotating the ball screw.
 27. The plasma processing chamber of claim 19,wherein: the upper electrode assembly comprises at least one baffle forsupplying process gas into the gap; and an RF power supply is operableto supply RF power to the lower electrode to excite the process gas toproduce plasma.
 28. The plasma processing chamber of claim 19, furthercomprising a confinement ring assembly including at least oneconfinement ring configured to encircle the gap and thereby confine theplasma in the gap.